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Full text of "Research abstracts /National Advisory Committee for Aeronautics"

National Advisory Committee for Aeronautics 



NO. 82 



Research Abstracts 



MAY 4, 1955 



CURRENT NACA REPORTS 



NACA Rept. 1169 

MATRIX METHODS FOR DETERMINING THE 
LONGITUDINAL -STABILITY DERIVATIVES OF AN 
AIRPLANE FROM TRANSIENT FLIGHT DATA. 
James J. Donegan. 1954. ii, 20p. diagrs., 6 tabs. 
(NACA Rept. 1169. Formerly TN 2902) 

Three methods are presented for calculating the lon- 
gitudinal stability derivatives from transient flight 
data. Several examples using flight data are given 
to illustrate the method. The results indicate the 
scatter which is typical of this type of analysis. 



NACA TN 3349 

APPLICATION OF THE GENERALIZED SHOCK- 
EXPANSION METHOD TO INCLINED BODIES OF 
REVOLUTION TRAVELING AT HIGH SUPERSONIC 
AIRSPEEDS. Raymond C. Savin. April 1955. 
71p. diagrs., photos., tab. (NACA TN 3349) 

The generalized shock-expansion method is applied 
to obtain solutions to the flow field about pointed 
bodies of revolution at high supersonic airspeeds 
and small angles of attack. Simple explicit expres- 
sions are obtained for the surface Mach numbers 
and surface pressures in the special case of slender 
bodies. In the case of inclined cones, algebraic 
solutions are obtained defining the entire flow field. 
Experimental pressure-distribution data for cones 
and ogives at Mach numbers from 3 to 5 are 
included. 



NACA TN 3372 

FLIGHT MEASUREMENTS OF BASE PRESSURE ON 
BODIES OF REVOLUTION WITH AND WITHOUT 
SIMULATED ROCKET CHAMBERS. Robert F. Peck. 
April 1955. 18p. diagrs., photo. (NACA TN 3372. 
Formerly RM L50I28a) 

Base pressures were measured on fin-stabilized 
bodies of revolution with and without rocket cham- 
bers and with and without a converging afterbody. At 
Mach numbers between 0. 7 and 1. 2, the results 
show that the presence of a "cold" rocket chamber 
increased the pressure (less suction) over the center 
portion of the bases. The effects of rocket chambers 
on pressures near the edge of the bases were not as 
consistent throughout the Mach number range nor as 
appreciable at most speeds as were the effects on 
pressures measured on the center line. 






NACA TN 3406 

A SELF-EXCITED, ALTERNATING-CURRENT, 
CONSTANT -TEMPERATURE HOT-WIRE ANEMOM- 
ETER. Charles E. Shepard. April 1955. 29p. 
diagrs., photos. (NACA TN 3406) 

The hot-wire anemometer described herein was used 
to study turbojet-engine compressor rotating stall 
and surge. The system was capable of measuring 
flow over a frequency range of zero to 500 cycles per 
second. A self-sustaining, 8 kilocycle-per-second 
oscillation was used to heat the wire in a constant- 
temperature system. The relatively rugged, large- 
diameter wire allowed the use of the anemometer 
during the full-scale performance testing of cpmv 
pressors and turbojet engines. The commercial 
audio-frequency amplifier used reduced the cost and 
the time required to build the anemometer. 

O 

NACA TN 3410 

VARIATION OF LOCAL LIQUID-WATER CONCEN- 
TRATION ABOUT AN ELLIPSOID OF FINENESS 
RATIO 10 MOVING IN A DROPLET FIELD. Rinaldo 
J. Brun and Robert G. Dorsch. April 1955. 51p. 
diagrs., photo., tab. (NACA TN 3410) 

Trajectories of water droplets about an ellipsoid of 
revolution with a fineness ratio of 10 (10 percent 
thick) in flight through a droplet field were computed 
with the aid of a differential analyzer. Analyses 
of these trajectories indicate that the local concen- 
tration of liquid water at various points about an 
ellipsoid varies considerably and under some con- 
ditions may be several times the free-stream con- 
centration. Curves of the local concentration factor 
as a function of spatial position were obtained and 
are presented in terms of dimensionless parameters 
that describe flight and atmospheric conditions. 

NACA TN 3423 

METHOD OF CONTROLLING STIFFNESS PROPER- 
TIES OF A SOLID -CONSTRUCTION MODEL WING. 
Norman S. Land and Frank T. Abbott, Jr. April 
1955. 21p. diagrs., photos., tab. (NACA TN 3423) 

A simple method is presented for controlling the 
bending and torsional stiffnesses of a solid- 
construction model wing. The method consists of 
weakening the wing by drilling holes through the 
wing normal to the chord plane. Aerodynamic con- 
tinuity is maintained by filling the holes with a 
relatively soft material. The important parameters 
controlling the stiffnesses are the amount of mate- 
rial removed by drilling the ratio of hole diameter 
to wing thickness, and the plan-form pattern of the 
holes. Data are given which may be used for pre- 
dicting the stiffness of a model wing weakened in 
this manner. 



•AVAILABLE ON LOAN ONLY. 

ADDRESS REQUESTS FOR DOCUMENTS TO NACA, 1512 H ST., NW., WASHINGTON 25, D. C, CITING CODE NUMBER ABOVE EACH TITLE, 

THE REPORT TITLE AND AUTHOR. 






NACA TN 3435 

A STATISTICAL STUDY OF WING LIFT AT GROUND 
CONTACT FOR FOUR TRANSPORT AIRPLANES. 
Dean C. Lindquist. April 1955. 18p. diagrs., tab. 
(NACA TN 3435) 

A brief statistical study of the value of the wing-lift 
factor Kl at the instant of ground contact during 
landing is presented for four transport airplanes. 
Frequency distributions and probability distributions 
of the wing-lift factor were determined from accel- 
eration measurements on VGH records of 2,049 land- 
ings in routine airline operations. The results indi- 
cate that the mean value of Kl is very nearly 1, 
that in 95 percent of all the landings the lift factor 
did not vary from the mean value by more than ±0.1, 
and that the probability of obtaining a value of K^ 
as low as 0.8 or as high as 1.2 is approximately 1 
in 10,000. 



NACA TN 3437 

PRELIMINARY INVESTIGATION OF A SUBMERGED 
AIR SCOOP UTILIZING BOUNDARY-LAYER 
SUCTION TO OBTAIN INCREASED PRESSURE 
RECOVERY. Mark R. Nichols and P. Kenneth 
Pierpont. April 1955. 72p. diagrs., photos., 
2 tabs. (NACA TN 3437. Formerly RM L50A13) 

This paper presents results of low-speed tests of a 
submerged inlet consisting essentially of a conven- 
tional scoop located in a dimple in the fuselage sur- 
face. Boundary-layer-control systems investigated 
are shown to provide important increases in per- 
formance. It appears that the flow instability fre- 
quently encountered in the case of twin internally 
coupled inlets will be avoided for design high-speed 
inlet-velocity ratios as low as 0.5. 



NACA TN 3445 

DESIGN AND PERFORMANCE OF THROTTLE- 
TYPE FUEL CONTROLS FOR ENGINE DYNAMIC 
STUDIES. Edward W. Otto, Harold Gold and Kirby 
W. Hiller. April 1955. 39p. diagrs., photo. 
(NACA TN 3445) 

The results of an analytical and experimental inves- 
tigation of the steady-state and dynamic character- 
istics of three types of throttle-controlled fuel sys- 
tems are presented. The investigation covers the 
effect of output pressure on the controlled flow and 
the dynamic response of output flow to throttle move- 
ment. Results show that linearized analysis pro- 
vides an adequate description of the dynamic response. 
The best system tested showed a usable frequency 
response to 300 cycles per second. 



NACA TN 3498 

EXPLORATORY INVESTIGATION OF AN AIRFOIL 
WITH AREA SUCTION APPLIED TO A POROUS. 
ROUND TRAILING EDGE FITTED WITH A LIFT- 
CONTROL VANE. Robert E. Dannenberg and James 
A. Weiberg. April 1955. 55p. diagrs., photos., 
2 tabs. (NACA TN 3498) 



NACA 

RESEARCH ABSTRACTS NO. 82 

A two-dimensional wind-tunnel investigation has been 
made of an NACA 65i-012 airfoil modified with a 
porous, round trailing edge fitted with a small vane. 
Area suction was applied and the vane was used to 
fix the rear stagnation point. The effects of varia- 
tions of the chordwise extent of suction and of the 
vane geometry were investigated with the aim of at- 
taining high maximum lift with low suction quantity. 



BRITISH REPORTS 



N-36530^ 

Royal Aircraft Establishment (Gt. Brit. ) 
AN INVESTIGATION OF THE TEMPERATURE 
GRADIENTS ARISING FROM KEROSENE FIRES ON 
WATER. Jean Birchall, M. D. Knowles and J. A. 
Campbell. November 1954. lip. diagrs., photos. 
(RAE Tech. Note Mech.Eng. 192) 

When kerosene is burning on the surface of still 
water for short periods, the upper layer of water 
will reach boiling point, but there is a negligible 
temperature change at depths greater than 1 inch. 
Temperature gradients of the order of 600° C per 
inch, measured in the vertical plane, occur im- 
mediately above the water level, and of 100° C per 
inch, immediately below. Clearly defined effects 
are produced on metal specimens partially sub- 
merged in the water. 



N-36531* 

Royal Aircraft Establishment (Gt. Brit. ) 
A COUNTER CHRONOMETER FOR THE CALIBRA- 
TION OF PULSE INTERVALS IN MICROSECONDS. 
H. W. P. Knapp. November 1954. 23p. diagrs., 
photo. (RAE Tech. Note GW 346) 

An electronic chronometer for the measurement of 
pulse intervals from 20 microseconds to 1.7 milli- 
seconds is described with particular reference to the 
calibration of a pulse position system. The accuracy 
is 1 microsecond for a single count and about 0.25 
microsecond for a run of 10 successive counts. 



N-36533* 

Royal Aircraft Establishment (Gt. Brit. ) 
PRESSURE LAG IN PIPES WITH SPECIAL REF- 
ERENCE TO AIRCRAFT SPEED AND HEIGHT 
MEASUREMENTS. Keith Smith. November 1954. 
33p. diagrs.. photos. (RAE Aero 2507) 

A new method of applying lag corrections in flight is 
presented. It is based on the results of ground tests 
employing simulated steady dives and is shown to be 
more accurate than the method of Charnley using the 
response to a step input. The errors involved in 
measurement of lag in a pull-out are considered 
theoretically and are shown to be just appreciable in 
certain cases. Instrument lag is also briefly touched 
upon. A routine procedure for lag correction in 
flight is given. 



NACA 

RESEARCH ABSTRACTS NO. 82 

N-36534' 

Royal Aircraft Establishment (Gt. Brit.) 
INTERIM NOTE ON THE DESIGN AND DEVELOP- 
MENT OF A LABORATORY APPARATUS TO STUDY 
THE HIGH SPEED IMPACT BETWEEN A LIQUID 
DROP AND A SURFACE. D. C. Jenkins. December 
1954. 25p. diagrs., photos. (RAE Tech. Note Mech. 
Eng. 193) 

An apparatus is described which can be used for the 
study of the high-speed impact between a liquid drop 
and a surface. The apparatus has been used at 
speeds up to 800 ft/sec. Further development is 
described which will add to the scope of the appara- 
tus. 



N-36535* 

Royal Aircraft Establishment (Gt. Brit. ) 
HOT HARDNESS TESTS ON SOME TITANIUM 
ALLOYS. D. M. Leggett and D. A. Sutcliffe. 
October 1954. 18p. diagrs., photos., 4 tabs. (RAE 
Tech. Note Met. 206) 

The construction of a hot hardness tester is describ- 
ed. Details are given of the method of carrying out 
tests. The results of tests on some experimental 
and commercial titanium alloys are given, together 
with results of tests on stainless steel and Nimonic 
95. 



N-36536* 

Royal Aircraft Establishment (Gt. Brit. ) 
THE DETERMINATION OF COEFFICIENTS OF 
HEAT TRANSFER TO A ROCKET MOTOR NOZZLE 
BY A TRANSIENT METHOD: PART H. W. S. Long. 
December 1954. 19p. diagrs., 2 tabs. (RAE Tech. 
Note RPD 114) 

The measurements of heat transfer described in this 
note were made using a solid copper nozzle with an 
internal profile symmetrical about the throat. By 
this means it was possible to determine values at 
the throat of the nozzle and in the subsonic and 
supersonic regions of gas flow. The rate of heat 
transfer across the gas boundary layer was measured 
by determining the quantity of heat conducted into the 
nozzle by the transient measurement of tempera- 
tures at various points within it during the running 
time of the motor. The main purpose of the five 
firings described was to check the reproducibility of 
temperature measurements before embarking upon a 
comprehensive program. The reproducibility was 
found to be good. 



N-36540* 

Ministry of Supply (Gt. Brit. ) 

A REVIEW OF THE PROBLEM OF ABATING THE 
NOISE FROM AIRCRAFT. December 1954. 5p. 
(Ministry of Supply. NC 150) 

The problem of abating noise from aircraft has been 
reviewed, with particular emphasis on the reduction 
of noise in the vicinity of airports. This review 
states briefly the salient facts concerning the noises 
from different sources and the possibilities of re- 
ducing them. The general conclusion is that, so far 



as present knowledge goes, no drastic reduction of 
noise can be achieved without introducing very great 
economic penalties. 



N-36541* 

Royal Aircraft Establishment (Gt. Brit. ) 
THE USE OF RESIN-GLASS LAMINATES FOR BAT- 
TERY CONTAINERS. M. M. Cornford and E. 
Haythornthwaite. November 1954. 16p.,7tabs. 
(RAE Tech. Note Chem. 1241) 

A study has been made of the factors affecting the 
resistance of glass fabric-resin fabrications to bat- 
tery acid with a view to their use in battery con- 
tainers. Polyester resins can be obtained which are 
resistant to the attack of the electrolyte. Low alkali 
glass is seriously attacked by battery acid and the 
use of high alkali glass in this application is recom- 
mended. Increased resistance of polyester resin 
glass fabric laminates to attack by battery acid is 
obtained if a finish is applied to the glass surface to 
obtain the strongest possible resin to glass bond on 
lamination. 



N-36542* 

Ministry of Supply (Gt. Brit. ) 

RESEARCH ON MOULDED DURESTOS AIRCRAFT 

STRUCTURES. FINAL REPORT - JUNE 1954. 161p. 

diagrs., photos., 53 tabs. (Ministry of Supply. 

S & TM 15/54) 

The problem in this investigation was to establish a 
method of design and manufacture for certain type 
wing structures in the plastic material Durestos. 
The main objectives were to achieve efficiency on a 
strength-weight basis and a high rate of production 
at a cost far less than that normally associated with 
aircraft manufacture. It has been established that 
the first object can be met. In regard to the second 
object, further work on two different lines relating 
to workshop technology would need developing before 
mass production could be undertaken without risk of 
delays; the first relates to moulding tool manufacture 
while the second relates to "flock injection moulding" 
of the wing stiffening structure, for example, rib and 
spanwise internal flanges. 



MISCELLANEOUS 

N-35833 

Advisory Group for Aeronautical Research and 
Development. PAPERS PRESENTED AT THE 
FIFTH MEETING OF THE WIND TUNNEL AND 
MODEL TESTING PANEL: MEASUREMENT OF 
AERODYNAMIC FORCES ON OSCILLATING AERO- 
FOILS. A. I. van de Vooren, Nationaal Luchtvaart- 
laboratorium. A REVIEW OF THE TECHNIQUES 
OF MEASURING OSCILLATORY AERODYNAMIC 
FORCES AND MOMENTS ON MODELS OSCILLATING 
IN WIND TUNNELS IN USE ON THE CONTINENT. 
Jacques Valensi, Universite d'Aix-Marseille; 
APPENDIX: SYNTHETICAL METHODS FOR STUDY 
OF DYNAMIC FLIGHT PROPERTIES. E. Billion, 
ONERA. METHODS AND RESULTS OF NON- 
STATIONARY AIRFOIL THEORY. R. Timman, 
Nationaal Luchtvaartlaboratorium. TECHNIQUES 
OF MODEL TESTING IN FREE FLIGHT. Joseph A. 
Shortal, National Advisory Committee for Aero- 



nautics. JET -ENGINE -DRIVEN WIND TUNNELS. 
F. B. Greatrex, Rolls-Royce, Ltd. SOME ASPECTS 
OF SUPERSONIC WIND TUNNELS OPERATING 
TECHNIQUES. John R. Markham, Massachusetts 
Institute of Technology. DEVELOPMENT OF 
INTERMITTENT WIND TUNNEL TECHNIQUE. 
J. Lukasiewicz, National Aeronautical Establish- 
ment, Canada. THE DESIGN OF LARGE HIGH- 
SPEED WIND TUNNELS. Ralph F. Huntsberger 
and John F. Parsons, National Advisory Committee 
for Aeronautics. NOTES ON THE DESIGN AND 
CONSTRUCTION OF THE WELDED STEEL STRUC- 
TURE FOR THE 8 FT X 8 FT HIGH SPEED WIND 
TUNNEL AT THE NATIONAL AERONAUTICAL 
ESTABLISHMENT, BEDFORD. W. Wadkin and 
T. Barnes, British Ministry of Works. DESIGN 
AND CONSTRUCTION ASPECTS OF HIGH POWER 
WIND TUNNEL DRIVE SYSTEMS AND LARGE 
DIAMETER WIND TUNNEL COMPRESSORS. James 
Clark, Lovelace Foundation for Medical Education 
and Research. (Presented at Scheveningen Nether- 
lands Conference, May 3-7, 1954) 192p. diagrs., 
photos. (Advisory Group for Aeronautical Research 
and Development. AG15/P6) 



DECLASSIFIED NACA REPORTS 



NACA RM E51C27 

CRITERIONS FOR PREDICTION AND CONTROL OF 
RAM-JET FLOW PULSATIONS. William H. 
Sterbentz and John C. Evvard. May 16, 1951. 63p. 
diagrs., photos. (NACA RM E51C27) (Declassified 
from Confidential, 4/14/55) 

Results of a theoretical and experimental study of 
ram-jet diffuser flow pulsing, commonly referred to 
as a "buzz condition, ■ with and without combustion 
are presented. The theoretical approach to the prob- 
lem is a simplified treatment of the ram jet likened 
to act as a Helmholtz resonator. The theoretical 
resonance criterions reasonably predicted the 
occurrence of diffuser-flow pulsations. 



NACA RM E51D19 

EXPERIMENTAL INVESTIGATION OF TYPICAL 
CONSTANT- AND VARIABLE -AREA EXHAUST 
NOZZLES AND EFFECTS ON AXIAL-FLOW 
TURBOJET -ENGINE PERFORMANCE. Lewis E. 
Wallner and John T. Wintler. July 1951. 43p. 
diagrs., photos. (NACA RM E51D19) (Declassified 
from Confidential, 4/14/55) 

A study of the performance of constant- and variable- 
area exhaust nozzles and their effects on turbojet 
engines has been made from data obtained in the 
NACA Lewis altitude wind tunnel. The aspects 
covered include exhaust -nozzle velocity and flow co- 
efficients at pressure ratios up to 3.6, a comparison 
of full- and small-scale nozzle data, and influence of 
exhaust nozzles on engine specific fuel consumption, 
thrust control, and afterburner performance. 



NACA 

RESEARCH ABSTRACTS NO. 82 



NACA RM E52D30 

INVESTIGATION OF POWER EXTRACTION CHAR- 
ACTERISTICS AND BRAKING REQUIREMENTS OF A 
WINDMILLING TURBOJET ENGINE. Curtis L. 
Walker and David B. Fenn. July 1952. 31p. diagrs., 
tab. (NACA RM E52D30) (Declassified from 
Confidential, 4/14/55) 

An investigation was conducted in an altitude chamber 
at the NACA Lewis Laboratory to determine the 
power extraction and braking characteristics of a 
windmilling single-spool axial-flow turbojet engine of 
the 5000-pound thrust class over a range of altitudes 
from 5000 to 50, 000 feet and flight Mach numbers 
from 0.2 to 1.0. The constant applied torque required 
to stop the rotation of a windmilling engine in 0.2 
minute at a simulated altitude of 40,000 feet was found 
to be 99 foot-pounds at a flight Mach number of 0.2 
and 620 foot-pounds at a flight Mach number of 1.0. 
The torque required to stop the engine in 0.2 minute at 
a flight Mach number of 0.4 decreased from 290 foot- 
pounds as altitude was increased from 5000 to 
50,000 feet. 



NACA RM E52I24 

AMPLITUDE OF SUPERSONIC DIFFUSER FLOW 
PULSATIONS. William H. Sterbentz and Joseph 
Davids. December 1952. 23p. diagrs. (NACA 
RM E52I24) (Declassified from Confidential, 4/14/55) 

A theoretical method for evaluating the stability 
characteristics and the amplitude and frequency of 
pulsation of ram-jet engines without heat addition is 
presented. Theory and experiment show that the 
pulsation amplitude of a high-mass-flow ratio dif- 
fuser having no cone surface flow separation in- 
creases with decreasing mass flow. The theoretical 
trends for changes in amplitude, frequency, and 
mean-pressure recovery with changes in plenum- 
chamber volume were experimentally confirmed. 
For perforated, convergent-divergent-type diffusers, 
theory and experiment show the existence of a sta- 
bility hysteresis loop on the pressure-recovery 
mass-flow-ratio curve. 



NACA RM L52A18 

AN ANALYSIS OF BUZZING IN SUPERSONIC RAM 
JETS BY A MODIFIED ONE -DIMENSIONAL NON- 
STATIONARY WAVE THEORY. Robert L. Trimpi. 
March 1952. 72p. diagrs., photos. (NACA 
RM L52A18) (Declassified from Confidential, 
4/14/55) 

Experimental instantaneous pressure records of sim- 
ulated ram-jet models without heat addition showed 
that they buzzed in a manner governed internally by 
quasi-one-dimensional (plane-wave) theory, a manner 
which is not compatible with the laws of the Helmholtz 
(spherical-wave) theory. A theory applicable to the 
buzzing problem was obtained through modification of 
the one-dimensional, unsteady-flow theory. Theoret- 
ical computations of the pressure-time curves agreed 
closely with the experimental records. A possible 
simulation of the buzzing in ram jets with combustion 

by the test of a cold-flow model in which a contrac- 
tion in area replaces the combustion chamber is also 
discussed. 



NACA 

RESEARCH ABSTRACTS NO. 82 

NACA RM L52B14 

FLIGHT MEASUREMENTS OF THE LATERAL STA- 
BILITY AND CONTROL CHARACTERISTICS OF A 
HIGH-SPEED FIGHTER AIRPLANE. H. L. Crane, 
A. R. Beckhardt and C. E. Matheny. September 
1952. 50p. diagrs., tab. (NACA RM L52Bi4) 
(Declassified from Confidential, 4/14/55) 

Results are presented of measurements made of con- 
trols-free lateral oscillations, sideslips, rudder 
kicks, and aileron rolls at 10,000 at Mach numbers 
up to 0.815 and 30,000 feet at Mach numbers up to 
0.84. The variations of the static derivatives ob- 
tainable from the sideslip data with Mach number are 
presented. Discussion of the controls-free lateral 
oscillations and of the tendency toward rudder snak- 
ing is included. 



NACA RM L52D08 

PRELIMINARY STUDY OF SOME FACTORS WHICH 
AFFECT THE STALL-FLUTTER CHARACTERIS- 
TICS OF THIN WINGS. A. Gerald Rainey. July 1952. 
33p. diagrs., photo., tab. (NACA RM L52D08) 
(Declassified from Confidential, 4/14/55) 

The results of an exploratory, analytical, and experi- 
mental study of some of the factors which might be of 
importance in the stall flutter of thin wings are pre- 
sented. The factors considered were Mach number, 
Reynolds number, density, aspect ratio, sweepback, 
structural damping, location of torsion nodal line, 
and concentrated weights. - 



NACA RM L52D10 

PRELIMINARY EXPERIMENTAL INVESTIGATION 
OF THE FLIGHT OF A PERSON SUPPORTED BY A 
JET THRUST DEVICE ATTACHED TO HIS FEET. 
C. H. Zimmerman, Paul R. Hill and T. L. Kennedy. 
January 1953. 31p. diagrs., photos., 2 tabs. 
(NACA RM L52D10) (Declassified from Confidential, 
4/11/55) 

An investigation has been made of the stability and 
controllability in space of an arrangement compris- 
ing a man standing on a small platform which is 
rigidly connected to a jet nozzle having its thrust 
opposed to the pull of gravity. A man can stand 
stably on a jet-supported platform with little or no 
practice. Factors which would be thought to be dis- 
turbing, such as gyroscopic couples, off-center 
weights, inertia of the platform, and unsteady wind 
velocity, had no objectionable effects. A high degree 
of maneuverability in translational flight within the 
confines of a limited space was demonstrated. 



NACA RM L53G28 

A THEORY FOR STABILITY AND BUZZ PULSATION 
AMPLITUDE IN RAM JETS AND AN EXPERIMEN- 
TAL INVESTIGATION INCLUDING SCALE EFFECTS. 
Robert L. Trimpi. October 1953. 75p. diagrs., 
photos., 3 tabs. (NACA RM L53G28) (Declassified 
from Confidential, 4/14/55) 

From a theory developed on a quasi -one -dimensional- 
flow basis, it is found that the stability of the ram 
jet is dependent upon the instantaneous values of 
mass flow and total pressure recovery of the super- 



sonic diffuser and immediate neighboring subsonic 
diffuser. Conditions for stable and unstable flow are 
presented. The theory developed in the paper is in 
agreement with the experimental data of the papers 
of both Sterbentz and Evvard and Ferri and Nucci. A 
simple theory for predicting the approximate ampli- 
tude of small pressure pulsation in terms of mass- 
flow decrement from minimum -stable mass flow is 
developed and found to agree with experiments. 
Cold-flow tests at a Mach number of 1.94 of ram-jet 
models having scale factors of 3.15:1 and Reynolds 
number ratios of 4.75:1 with several supersonic 
diffuser configurations showed only small variations 
in performance between geometrically similar models. 
The conditions at which buzz originated were nearly 
the same for the same supersonic diffuser (cowling- 
position angle) configurations in both large and 
small diameter models (both Reynolds numbers). 
There was no appreciable variation in stability limits 
of any of the models when the combustion-chamber 
length was increased by a factor of three. The 
unsteady-flow performance and wave patterns were 
also similar when considered on a reduced-frequency 
basis depending on the relative lengths of the model. 
The velocity profile in the combustion chamber at 
both Reynolds numbers was appreciably influenced by 
an angle of attack of 1/2°. 



NACA RM L54B12a 

FLIGHT TESTS OF A MAN STANDING ON A PLAT- 
FORM SUPPORTED BY A TEETERING ROTOR. 
Paul R. Hill and T. L. Kennedy. March 1954. 26p. 
diagrs., photos. (NACA RM L54B12a) (Declassified 
from Confidential, 4/11/55) 

Following the lead given by successful flight tests of 
a man standing on a jet -supported platform, flight 
tests were made of a man standing on a teetering- 
rotor -supported platform. The rotor was 7 feet in 
diameter as was driven by compressed-air jets at 
the tips supplied to the machine by air hoses. Hover- 
ing and limited translational flights from 1- to 7 -foot 
elevations were made both indoors and outdoors. 
The stability and controllability of the machine and 
flyer combination were satisfactory. 



NACA RM L54G14a 

A PRELIMINARY FLIGHT INVESTIGATION OF AN 
OIL-FLOW TECHNIQUE FOR AIR-FLOW VISUALI- 
ZATION. Harold I. Johnson and Robert G. Mungall. 
October 1954. 33p. diagrs., photos. (NACA 
RM L54G14a) (Declassified from Confidential, 
4/14/55) 

Preliminary experiments were made to evaluate a 
simple oil -flow technique for use in flight research. 
Photographs of oil flow on the wing of a swept-wing 
airplane in transonic flight and oil patterns remain- 
ing on the wing after flight at transonic speeds are 
presented. Also included are comparable shadow- 
graph and tuft pictures. The technique shows con- 
siderable promise, particularly for future transonic - 
and supersonic -flight research. 



NACA-Langley - 5-4-55 - 4M 



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POLICY OF NACA ON DISTRIBUTION OF THEIR PUBLICATIONS 

NACA Reports, Technical Notes, and Technical Memorandums are available for a period of 5 years, 
after that, most of them can be had only on a loan basis. All Wartime Reports are in this category. 
All loan material should be returned promptly at the expiration of the loan period to the following address 
Langley Aeronautical Laboratory, Langley Field, Virginia - ATTENTION: Mr. Walter H. Lee. 
British publications currently listed on the Research Abstracts are available only on loan. However, 
should a British paper be of particular interest and if you will so advise this office, your name will be 
placed on our waiting list to receive a copy if and when retention copies can be furnished. 

Please fill in the requested information below since the above part of this form will be returned with the 
documents requested. 



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City, Zone No., and State. 



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UNIVERSITY OF FLORIDA 



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